auto trans stall speed

[jim ross]

I have owned my 1984 928s auto for 3 years now, and have just now realized after reading workshop manuals that....stall speed should be around 2400 rpm. Well since the day i picked it up it engages as soon as its put in gear...(1000rpm). The car has always gone down the road nicely, shifts fine, and accelerates well. But this is a worry to me, the shop manual says that this may indicate a siezed "oneway clutch". Has anyone seen this before???

[Danglerb]

I'm not an AT person, but engage isn't stall, stall is the brakes on tires still about to spin foot on the gas RPM.

[atb928]

Jim,

Stall speed is measured by braking against the engine torque on the converter. Like Danglerb says, your tranny will engage earlier than the stall speed, but you should be able to apply the parking brake, then apply full force on the foot brake, and take the engine up to 2200 rpms, but no higher then 2600 rpms, before the engine stalls out due to the load. WSM say this test should last no longer then 5 seconds (understandably ).
If the car appears to be driving fine, I wouldn't worry about it. I've had my 928 at the strip a few times, and I know powerbraking at even at 1500rpms is not pleasant . I launch at 1K rpms because the car feels like it wants to fold in on itself when your holding the motor back at any higher rpm.

[928SS]

stall on the 928 is about 1500rpm and w/2.20 rear end it's a boat off the line... I rebuilt my TC to 2100 or so and it launches like a missle. but before it was outrun by minivans off the line w/a stock motor and 2.20 gears.

[jim ross]

Thanks for the info guys!! I misunderstood the meaning of "stall speed". I was under the impression that it was when the tranny actually engaged. I will sleep well tonite! THANKS! J

[atb928]

Another thing to bear in mind is that WSM have an offset calculation that needs to be taken into account based upon your elevation. The factory stall speed specs are assuming you're at sea level.

Just as a side note, the LH Euro's have the highest stock stall speed, and I've heard of rumors of folks installing Euro converters on US spec cars to help with the launch.

[Danglerb]

Changing the stall to whatever you like I think is something many shops can do. I've heard that some just take out some fins in the torque converter, and that can't be good, but people have been messing with auto transmissions to make them go fast a LONG time.

I've never gotten a really straight forward answer from anybody on what it does to the day to day drivability, but it sounds to me like it suffers and MPG drops etc.